Lubricating grease compositions containing an alkylaminocarbazole



States Patent 2,990,368 LUBRICATING GREASE COMPOSITIONS CON TAINING AN ALKYLAMINOCARBAZOLE Ralph B Thompson,.Hinsdale, Ill., assignor, by mesne assignments, to Universal Oil Products Company, Des ll Plaines, 111., a corporation of Delaware No Drawing. Filed May 9, 1958, Ser. No. 734,118

. 1 12' Claims. (Cl. 2.'5240.7)

This invention relates to the stabilization of synthetic grease and more particularly to a novel method of preventing and/ or retarding deterioration thereof. The present application is a continuation-in-part of my earlier'application Serial No. 537,539, filed September 29, 1955, now Patent No. 2,864,676.

Synethetic greases include lithium base grease, sodium base grease, potassium base grease, calcium base grease, barium base grease, strontium base grease, aluminum base grease, beryllium base grease, cadmium base grease, magnesium base grease, lead soap grease, complex soap grease, etc., or mixtures known as mixed base greases. These greases are solid or semi-solid gels and in general are prepared by the addition to mineral oils of hydrocarbon-soluble metal soaps or salts of higher fatty acids as, for example, lithium stearate, calcium stearate, aluminum naphthenate, etc. In another method, the metal soap or salt. is added to synthetic oils including, for example, di- (2-ethylhexyl) sebacate or azelate, di-tetradecyl sebacate, tricresyl phosphate, polyalkylene oxides, silicones, alkyl or alkyl aryl polysiloxanes or blends of these with petroleum oil. The grease may contain thickening agents such as silica, carbon black, polyacrylates, talc, polyamides, alkylureas, etc. Another type of grease is prepared from oxidized petroleum wax to which the saponifiable base is combined with the proper amount of the desired 's'aponifying agent, and the resultant mixture processed to produce a grease.

' In one embodiment the present invention relates to a method of stabilizing synthetic grease which comprises incorporating therein a stabilizing concentration of an alkylaminocarbazole inhibitor.

In a specific embodiment the present invention relates to a method of stabilizing lithium base grease which comprises incorporating therein from about 0.( )001% to about 5% by Weight of 3-octylaminocarbazole.

In still another embodiment, the present invention relates to a synthetic grease containing a stabilizing concentration of the inhibitor herein set forth. 7

The stabilization of synthetic grease presents problems considerably different from those encountered in the stabilization of petroleum greases, for example. Synthetic greases have been developed for use at high temperatures and therefore require a stabilizing agent which will be'etfective at the high temperatures encountered during use of the synthetic grease. Furthermore, the chemical composition of synthetic greases is difi'ferent from the chemical composition of petroleum greases, and these different properties accordingly present different problems. 7 In accordance with the present invention stabilization of synthetic grease is accomplished by incorporating therein an alkylaminocarbazole inhibitor. Illustrative inhibitors include l-ethylaminocarbazole, l-propylaminocarbazole, l-butylaminocarbazole, l-amylaminocarbazole, 1.- hexyla'minocarbazole, l-heptylaminocarbazole, l-octylaminocarbazole, l-nonylaminocarbazole, l-decylaminocarbazole, l-undecylaminocarbazole, l-dodecylarninocarbazole, etc., 3-ethylaminocarbazole, 3-propylaminocarbazole, S-butylaminoca-rbazole, 3-amylaminocarbazole, 3- hexylaminocarbazole, 3-heptylaminocarbazole, 3-octy1- aminocarbazole, 3-nonylaminocarbazole, 3-decylaminocarbazole, 3-undecylaminocarbazole, 3-dodecylaminocarnocarbazole, 3,6-dibutylaminocarbazole, 3,6-diamylami nocarbazole, 3,6-dihexylaminocarbazole, 3,6-diheptylami nocarbazole, 3,6-dioctylaminocarbazole, 3,6-dinonylauii nocarbazole, 3,6-didecylaminocarbazole, 3,6-diundecyla minocarbazole, 3,6-didodecylaminocarbazole,etc., 1,3,63,- tetraethylaminocarbazole, 1,3,,8-tetrapopylaminocanbazole, l,3,6,8-tetrabutylaminocarbazole, 1,3,6,8-tetraam ylaminocarbazole, 1,3,6,8-tetrahexylaminocarbazole, 1,3,6 8 tetraheptylaminocarbazole, 1,3,6,8-tetracotylami n 0 cat I,- bazole, etc. 2,3,6,7-tetraethylaminocarbazole,; 2 ,3, 6,- 7.,- aminocarbazole, 2,3,6,7 -tetrapropylamino c a r b ;a z o l e, 2,3,6,7-tetrabutylaminocarbazole, 2,,3,6,7-tetraamylaminocarbazole, 2,3,6,7wtetrahexylaminocarbazole, 2,3,6,7-tetra} heptylaminocarbazole, 2,3,6,7 tetraoctylaminocarbazole, etc, It is understood that the specificcompounds set forth above are illustrative and that correspondingcompounds having the substitutions in other positions may be utilized. q

In another embodiment, aminocarbazoles also having a substituent attached to the imiuo nitrogen may be used. The imino nitrogen is the heterocyclic nitrogen in the S-memberedring. Illustrative examples jofin hibitors in this class include N-ethyl-3-ethylaminocarbazole, N-ethyl-S-propylaminocarbazole, .N-ethyl-3-butylj aminocarbazole, N-ethyl-3-amylaminocarbazole, Nwethyl; 3-hexylaminocarbazole, N-ethyl-3-heptylaminocarbazole, N-ethyl-3-octylaminocarbazole, etc., N-propyl-3-ethylaminocarbazole, N-pro'pyl-B-propylaminocarbazole, N- propyl-3-butylaminocarbazole, N-propyl-3-amylaminocarbazole, N-propyl-Shexylaminocarbazole, N-propyl-3- heptylaminocarbazole, N-propyl-3-octy1aminocarbazole, etc., N-buty1-3-ethylaminocarbazole, N-butyl-3-propylaminocarbazole, N-butyl-3-butylaminocarbazole, N-butyl- 3-amy1aminocarbaz0le, N-bu-tyl-3.-hexylaminocarbazole, N-butyl-3-heptylaminocarbazole, N-butyl-3-octylaminocarbazole, etc., N-amyl-3-ethylaminocarbazole, N-amyl- 3-propylaminocarbazole, N-amyl-3-butylarninocarbazole, N-amyLS-amylaminocarbazole, N-amyl-3 hexylaminocar bazole, N-amyI-S-heptylaminocarbazole, N-amyl-3-octylaminocarbazole, etc., N-hexyl-3-ethylaminocarbazole, N hexyl-B-propylaminocarbazole, N-hexyl-3-butylaminocar bazole, N-hexyl-3-amylaminocarbazole, N-hexyl-B-hexylaminooarbazole, N-hexyl 3 heptylaminocarbazole,--N- hexyl 3 octyl'aminocarbazole, etc., N ethyl 3,6- dipropylaminocarbazole, N propyl 3,6 dipropylaminocarbazole, N-butyl-3,6-dipropylaminocarbazole, N- amyl 3,6-dipropylaminocarbazole, N-hexyl-3,6-dipropyl aminocarbazole, etc., N-ethyl-2,3,6,7-tetraethylaminocare bazole, N-ethy1-2,3,6,7-tetrapropylaminocarbazole, N ethyl-2,3,6,7-tetrabutylaminocarbazole, N-ethyl-2,3, 6,7- tetraamylaminocarbazole, N-ethyl-,2,3,6,7-tetrahexy1ami nocarbazole, etc., N-propyl 2,3,6,7-'t etraethylarninocarbazole, N-propyl-Z,3,6,T-tetrapropylaminocarbazole, N- propyl-2,3,6,7-tetrabutylaminocarbazole, N-propyl-2,3,6,7- tetraamylamiuocarbazole, N-propyl-2,3,6,7-tetrahexylaminocarbazole, etc., N-pr'opyl 1,3,6,8-tetrapropylaminocarbazole, N-propyl 1,3,6,8-tetrabutylaminocarbazole, etc. Here again, it is understood that the specific compounds set forth above are illustrative and that other compounds containing an alkyl substituent attached to the imino nitrogen and also those containing this substituent and alkyl substituents attached to one or more of the amino nitrogens may be employed.

In another embodiment, the amino or alkylaminotetras hydrocarbazoles may be employed. Illustrative examples bazole, etc., 3,6-diethylaminocarbazole, 3,6-dipropylamiof compounds in this class include 6 propylamino-l ,2,3,4- tetrahydrocarbazole, 6-buty1amino-1,2,3,4-tetrahydroqar bazole, 6-amy1aminol,2,3,4-tetrahydrocarbazole, 6-hex -ylamino-1,2,3,4, tetrahydrocarbazole, etc, v

While the alkyl-substituted amino or p'olyaminocarbazoles' are preferred, it-isunders'toodthat substituted amino or' polyamino' c'arbazc les in which the substituent comprises other groups may be employed. The other groups preferably comprise hydrocarbon groups and will be selected from cycloallryl, a'ryl, alkaryl or aralkyl. In some cases, the substituent maycomprise an alkenyl or eycloalkenyl' group. In still other cases, the alkyl or'other hydrocarbon group may contain non-hydrocarbon comand/or sulfur.

It is understood" that mixtures of compounds may be employed. In fact, during the preparation of some of these compounds, '9. mixturecontaining two different 'alkylamino or polyalkylamino compounds is formed, and such mixture may be used.

It is apparent that numerous compounds may be prepared andutilized in accordance with the present invention; However, all of these compounds are not necesponents including those comprising oxygen, nitrogen sarily'equivalent and maybe oi diiferent effectiveness in the same or different greases. The particular compound The particular carbazole compound illustrated is a 3- alkylaminocarbazole. Again, it is understood that this formula is merely for illustrative purposes and that other suitable alkylamino, including poly-substituted compounds, may be employed.

The inhibitor compounds of the present invention may be prepared in any suitable manner. For example, aminocarbazole may be prepared by nitration of oarbazole to form the nitro-substituted compound, followed by reduc tion of the nitro group tothe amino group and by reductive alkylation to form the alkylarninocanbazole. The alkylsubstitution preferably is of secondary configuration; that is, the alkyl group is attached to the nitrogen atom at an intermediate carbon atom of the alkyl group. This substitution is obtained by utilizing a ketone in the reductive alkylation reaction. When a primary group is. desired, an aldehyde is used in the reductive alkylation step. 1 In general the inhibitor of the present invention is utilized in a concentration of from about 0,0001% to about 5% by weight of the grease. The exact concentration to be used will depend upon the particular grease 1 7 being treated. In most cases concentrations of from about v0.01% to about 3% by weight generally is employed.

with other additives incorporated in synthetic grease, including alcohols, esters, organic amines, polybutene, sul-furized fatty materials, sulfur chlorine compounds, dyes, perfumed materials, fillers, etc. In some cases, it may be of advantage to also include a metal deacti- It is understood that the inhibitor may be used along vator as, for example, disalicylal diamino propane, ethylene diamine tetraacetic acid tetrasodiurn salt, etc., or to include other additives such as tricresyl phosphate, trialkyl phenols includingv 2,6-di-tert-butyl-4-methylphenol, 2,4-di-tmethyhfi-tert-butylphenol, etc., alkylated diphenyl phenyl naphthyl amines, dialkyl phenyl ene diamines, phenotbia'zinaorganic selenium compounds, etc.,

7 "2,990,368 i is? 4 as well as corrosion inhibitors, extreme pressure additives, viscosity index improvers, etc. The inhibitor of the present invention may be utilized as such or in a suitable solvent including hydrocarbons, alcohols, glycols, ketones, others, etc. When desired, the inhibitor may beprepared asa mixture with one or more of these other additives and incorporated'in-this manner irithe grease or components'thereof. a

The inhibitor of the present invention may begincorporated in the grease in any suitable manneriand at any suitable stage of preparation. Thus, it may be added to one Tor more'components of the grease prior to compositing and processing thereof or it may be added to the mix at any time, preferably before final processing in order to obtain intimate mixing and dissolving of the inhibitor in the grease.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

Example I modified Norma-Hoffman method, in which a sample of the grease is placed in a bomb and oxygen is charged thereto. The bomb then is heated to 212 F., and the time required for a drop of 5 pounds pressure is taken as the induction period. In this run, a control sample of the grease (not containing this additive) had an induction period of 10 hours. On the other hand, a sample of the grease containing 1% by weight of 3-octylaminocarbazole had an induction period of 3'1 hours. Thus, it is seen that the inhibitor of the present invention served to improved considerably the stability of the grease.

Example 11 The run described in Example I was continued until a pressure drop of 30 pounds per square inch was obtained. In the control sample, this drop occurred after 23 hours. However, the sample containing 3-octylaminocarbazole ran for 122 hours before reaching the 30 pound pressure drop.

Example III The inhibitor of this example is 3-isopropylaminocarbazole. This compound has a melting point of 181"- .182 C. and a boiling point of 190 C. at 1 mm. pressure. This additive is incorporated in a calcium base grease in 'a concentration of 0.5% by weight and serves to increase the time required for a drop of five pounds pressure when the grease is evaluated in the modified Norma-Hofiman method described in Example 1.

Example IV The inhibitor of this example is 3,-6-diisopropylaminocarbazole, which compound has a boiling point of 170- 230 C. at 1 mm. pressure. 1.5% by weight of this inhibitor is incorporated in sodium base grease and serves to increase the time required for a drop of 5 pounds pressure when the grease is evaluated in the modified Norma-Hofiman method described in Example I;

Example V thickening amount of a metal soap of a higher fatty acid and a stabilizing concentration of analkylaminocarbazole inhibitor.

2. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a metal soap of a higher fatty acid and a stabilizing concentration of a polyalkylaminooarbazole inhibitor.

3. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of an alkylamino carbazole inhibitor.

4. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of a polyalkylaminocarbazole inhibitor.

5. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of 1-(2-octylaminocarbazole).

6. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of 3-octylaminocarbazole.

7. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of 3-isopropylamino carbazole.

8. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a lithium soap of a higher fatty acid and a stabilizing concentration of 3,6-diisopropy1- aminocanbazole.

9. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a calcium soap of a higher fatty acid and a stabilizing concentration of 3-octylaminocarbazole.

10. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of a calcium soap of a higher fatty acid and a stabilizing concentration of 3-isopropylaminocarbazole.

11. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of lithium stearate and from about 0.0001% to about 5% by weight of an alkylaminocarbazole inhibitor.

12. A lubricating grease composition consisting essentially of a major amount of a lubricating oil, a greasethickening amount of calcium stearate and from about 0.0001% to about 5% by weight of an alkylaminocarbazole inhibitor.

References Cited in the file of this patent UNITED STATES PATENTS 1,836,702 Christmann Dec. 15, 1931 2,370,552 Lincoln et a1. Feb. 27, 1945 2,374,098 Ingram Apr. 17, 1945 2,595,140 Heinrich Apr. 29, 1952 2,607,735 Sproule et a1. Aug. 19, 1952 2,652,366 Jones et a1. Sept. 15, 1953 

1. LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A LIBRICATING OIL, A GREASE THICKENING AMOUNT OF METAL SOAP OF A HIGHER FATTY ACID AND STABILIZING CONCENTRATION OF AN ALKYLAMINO CARBAZOLE INHIBITOR. 